The present invention relates to the production of lower boiling hydrocarbons by the reaction of higher boiling liquid hydrocarbons presence of methane and refinery off gases containing methane.
EP 89 310 discloses a process in which residual oil is sprayed into a hot gas containing methane. However the specification requires the use of hydrogen present in quantities such as to give a partial pressure of at least 0.3 MPa. The total pressures disclosed are of 2 MPa or higher. There is no suggestion that methane can react to give increase the amount of liquid cracking products, and the specification indicates that under the (high pressure) conditions used the use of high ratios of methane to hydrogen is disadvantageous.
In many parts of the world there are large deposits of natural gas. It would be desirable if this natural gas could be used to produce liquid hydrocarbons which would be more useful as fuels. Considerable amounts of higher boiling hydrocarbons whose molecular weight is too high for them to be satisfactory fuels for many purposes, particularly for transport, are also available in many countries. It would be desirable to find a way of producing relatively low boiling liquid hydrocarbons from both methane and high boiling hydrocarbons, preferably using the same process.
We have now found that by suitable choice of reaction conditions methane can be reacted with higher hydrocarbons so as to increase the yield of liquid cracking products.